There are two ways to specify field length. If a field has a constant length that is defined in the control file with a position specification or the data type and length, then it has a predetermined size. If a field's length is not known in advance, but depends on indicators in the record, then the field is delimited, using either enclosure or termination delimiters.
If a position specification with start and end values is defined for a field that also has enclosure or termination delimiters defined, then only the position specification has any effect. The enclosure and termination delimiters are ignored.
loc POSITION(19:31) loc CHAR(14)
In the second case, even though the exact position of the field is not specified, the length of the field is predetermined.
Enclosure delimiters surround a field, like the quotation marks in the following example, where "__" represents blanks or tabs:
Delimiters are specified with the control clauses
BY, as shown in the following example: